I disagree. It's not just the thd that influence the electronics sound, but other forms of distortions that most often ignored (imd, tid, phase distortion and just high order armonics). The way these distortions affect the sound is so strong that something like .1% is clearly audible and it can be much worse than a .2% from the speakers.
Yes, what we want are simple circuits with short signal path with as few active and passive components on the signal, and yet a good distortion performance.
I personally prefer open loop circuits but between one with 1% thd@1W and another with 0.01% with closed loop, I prefer the sound of the latter.
Here you can test your ability to hear distortion :Listening Test
I scored in the middle ground.Even 1% low order distortion was hard for me to differentiate.
0.1% low order is definitely not audible.
If you can you are an alien.
I scored in the middle ground.Even 1% low order distortion was hard for me to differentiate.
0.1% low order is definitely not audible.
If you can you are an alien.
Here is an older test on how much distortion we can hear :http://www.linearaudio.nl/Miscellaneous/langevin im in tape recorders.pdf
The test subject was non other then Les Paul.
The test subject was non other then Les Paul.
Designing for ultra low distortion is not hard anyway :http://www.linearaudio.nl/Documents/graeme feedback generalization.pdf
problem solved !?
problem solved !?
Problem with speakers is that the distortion you measure is steadystate....so you don't even count the Doppler distortion from multi-tone and the fact that magnet systems are very very nonlinear so a 2kHz on top of a 100 Hz may look quite odd.
On a smaller product like a preamp...distortion may be ca. valid measure, as we have somewhat control of impedance's in both ends.
But in the thread where you nailed my quote we were talking amplifiers driving speaker loads, and in that respect Distortion is a non measure. Or it says nothing about sonic qualities of the circuit.
On a smaller product like a preamp...distortion may be ca. valid measure, as we have somewhat control of impedance's in both ends.
But in the thread where you nailed my quote we were talking amplifiers driving speaker loads, and in that respect Distortion is a non measure. Or it says nothing about sonic qualities of the circuit.
It all depends on the playback chain where it is reproduced. I also scored on the middle (failing at 18/21) with work pc with emu1212 and a pair of Aurvana Live.
I second that...speakers and AMP interfacing is a key issue, how does an amplifier deal wit return-currents, how does it bleed back through the feedback.. ect ect.
And I must correct myself, your quote was indeed taken from this thread, but was pro or con an opamp circuit vs an simple discrete solution. where i preferred the simple in-spite of an on paper poorer performance. (sorry)
And I must correct myself, your quote was indeed taken from this thread, but was pro or con an opamp circuit vs an simple discrete solution. where i preferred the simple in-spite of an on paper poorer performance. (sorry)
Some work has being done :http://www.cordellaudio.com/papers/interface_intermodulation_distortion.pdf
But what is a "proper" design ?
But what is a "proper" design ?
I know this is not the proper place for it.... and it should have it own thread... bu to be honest the speaker model in Cordells paper is as good as none...
The hardship is including the nonlinear mechanics in the model. It's mainly the masses that creates the Back EMF that the amplifier has to deal-with..currents out of phase with the driving Voltage... I think there's one of the big differences in VFB vs CFB...sorry.. again not to change the thread, but merely a point of view worthy of concentration.
The hardship is including the nonlinear mechanics in the model. It's mainly the masses that creates the Back EMF that the amplifier has to deal-with..currents out of phase with the driving Voltage... I think there's one of the big differences in VFB vs CFB...sorry.. again not to change the thread, but merely a point of view worthy of concentration.
Yesterday i have finished the prototype of the I/V converter . And made some tests.
I must say, that i am very happy with the results.
As predicted the distortion is very low , and i can not measure it with the equipment that i have (emu1212m) better than 0.0003%. Anyway i post here a picture of 2,8 Volts rms output in 1kohm. 8ma p-p.
Gz
(I'm reading all thread, very educative)
I find this topic very, very interesting, and I have some ideas. I hope we can discuss that in a near future, just let me finish the pcb for this project.
Gz
(I'm reading all thread, very educative)
Glad i am not the only one that have learn something
. Telstar to use pcm1704 only need to change the output resistance and capacitor to have 1 volt rms at output you need 1kohm in parallel with 1.8nf .
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Yes you right , for some opamp that has a high bias current, but for opa2134 for example that has 5pA of bias current the voltage in 1 Meg is 5uV . so it is better to not have the resistance (less noise) i am sure you agree with me.
PCM1704 please
Yes PCM1704/02 me too please to help they have +/- 1.2mA at 1kohm, if we then could get 2v out I'll be happy.
Cheers George
the 1704 is "easy"... gain is changed by the output resistor, Sergio already gave some suggested values. If you then need more output, scale the resistor and cap accordingly. for low output DAC's it could be beneficial to use an output buffer, like the simple B1 or similar.
As the PCM1704 and also the TDA1541 operates +/- No counter-current is needed at the input.
As the PCM1704 and also the TDA1541 operates +/- No counter-current is needed at the input.
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